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I think it is possible to have a good scan and later SM show up hence the recomendation to rescan at 2.5 years old. An early scan just eliminates the worst affected I think.More information from those who have done rescans would be interesting.
Evelyn

Welcome to the board, Sue. It is a progressive condition and dogs need to be at least 2.5 to be given a grade on the grading programme. While an early scan gives a good indication for many dogs of where they might be heading, it won't guarantee an A dog, for example. Most neurologists familiar with scanning over time will be pretty good at estimating whether a scan shows reason to be concerned or not, on a dog under the grading age. Most in my experience will give some sort of general prognosis. AxA matings won;t guarantee clear dogs either, though the statistics are considerably higher. Non A dogs in matings have as far as I know yet to produce a single A offspring. But A to D produces very good results, too and for genetic diversity and to retain other good genes, breeders will need to use Ds too. Ideally more dogs will be scanned so more breeders will know of more A options.

The older the dog at the time of scan and breeding, the better with progressive conditions.

I recently had all four of my dogs scanned -- two are rescans of dogs first done at just over a year, which are now about to turn 5.

I haven't yet had time to post on my experience because I wanted to get pictures that I can post, so that people can see the scans and what they mean.

On his original scan in 2005, Leo, my dog with SM, was showing herniation, dilated ventricles, a kinked spinal cord and a small syrinx when totally asymptomatic at age 1 year 5 months. He was symptomatic, mildly, by age 2.5. Now he is moderately symptomatic, scratching and some tenderness on and off. His rescan showed his syrinx had not grown in length (it is quite short) but has widened quite a bit (width is the predictor of pain) and is now graded large. His ventricles remained the same. Jaspar, who was clear then for everything except perhaps some hind brain compression in 2005, remains without a syrinx and is confirmed as an A graded dog now that he is over 2.5. He has slightly enlarged ventricles now (the meaning of enlarged ventricles remains unknown -- some breeds naturally have very large ventricles -- but the size is recorded for scans).

Of my other two, Lily my rescue scanned with SM as I had expected -- the reason I never homed her (I run a rescue) was because she already had some suspicious scratching when she came in. If you have had a dog with SM and seen the difference in scratching you tend to know when it is a bit less likely to be 'normal scratching'. On the plus side, her scan was much better than I had guessed it would be (I stress again I was expecting this result; my concern was not that it would show SM but what the scan would show overall as to where she is now). Her syrinx is tiny and as she is three or four I wouldn't expect it to get a lot worse. It is important to stress that many of our dogs live with syrinxes all their lives and are easily managed; many will never require any treatment and we won't even know they have a problem because most of us do not scan our pet cavaliers. But breeding unscanned asymptomatic dogs is in my opinion another issue -- if my breeder had his original choice, Leo would have been bred at the time he was asymptomatic and if I hadn't scanned I'd never have known the difference. I also think his symptoms would not have been seen as a kennel dog in a breeding programme or even if he had been shown or lived indoors with a group of dogs by someone not looking for signs, probably til he was closer to 4-5).

Lucy, I am delighted to say, a 9 year old dog bred by Laura Lang of Roycroft Cavaliers in the US, had a superb scan -- clear of everything! Interestingly this result was predicted by some researchers, and I know confirms Laura's own theories about lines and selecting certain lines for health and she is a real tribute to her breeding programme in both health and personality. Lucy's scan was valuable for researchers who have few scans on older dogs. Lucy was totally clear for PSOM too.

I hope those details may give some insight.

When I get a chance I will do a detailed post on my trip and get up some images of the scans.

Lucy, I am delighted to say, a 9 year old dog bred by Laura Lang of Roycroft Cavaliers in the US, had a superb scan -- clear of everything! Interestingly this result was predicted by some researchers, and I know confirms Laura's own theories about lines and selecting certain lines for health and she is a real tribute to her breeding programme in both health and personality. Lucy's scan was valuable for researchers who have few scans on older dogs. Lucy was totally clear for PSOM too.

Thank you for posting this Karlin.
Thank you Laura for renewing our hope.

Wow, that is really impressive, Karlin! Two dogs out of four effectively scanning more or less clear. I have to ask: does anyone know if any breeders in the UK use Roycroft at all? It sounds like the genetics there would be a superb addition to a UK Cav breeding programme.

Karlin can I ask is Jasper symtomatic at all, has the new dilation in the ventricles given him any symptoms? do you notice a change at all? I would be interested in this.

No, why would he be symptomatic with anything? Jaspar remains a clear dog and is an A grade. He has a nice straight spinal cord, no syrinxes, and space around his brain on his scan.

Dilated ventricles are not known to mean much of anything (except when very large and indicating hydrocephalus of course) -- and a 1.5x enlargement is very little. The neurologists at the London conference noted this -- they said they record ventricle size because it is an obvious measurement but it has no 'use' at this point. Leo's ventricles haven't changed in nearly four years but he has gradually increased in symptoms. Leo has far more obvious symptoms than Lily but Lily has 3x ventricles and Leo's have never changed from 1.5x in Feb 2005. I know some other breeds have massive ventricles as well and there are likely to be familiy variations within a breed too. Leo and Jaspar are closely related and hence that may be why they have the exact same ventricle size despite one dog having SM and one being clear.

On Roycroft: Lucy goes almost immediately back to old UK dogs. So the issue is broader, of finding other clear dogs, through MRIing. Laura clearly has some excellent lines and she has been MRIing for some time and considering many aspects of breeding around SM and reducing MVD incidence too. Getting information on an older dog helps any breeder know how their lines do as they age and this is really helpful with progressive conditions like MVD and SM. For SM, knowing lines helps -- because clear dogs almost always have other clear dogs immediately around them -- which in turn is good evidence that clear dogs tend to produce far more clear dogs than any other option. I know Laura routinely also has dogs living til 14-15 and I certainly hope Lucy will be no exception.

There are definitely many clear dogs out there -- clear for SM that is, as almost all have the malformation -- but I mean also clear in the sense of a scan like Lucy's or Jaspar's where there aren't the additional features that might cause potential concern, like the cerebellum pushing well down into the spinal cord, or the kink in the spinal cord, or a lot of hindbrain crowding at the lower back of the skull where the brain can be really squished down (in some cavaliers the brain is so squashed it looks more like a ball shape ). I know of a good number of breeders with clear dogs and the more that are MRId, the more keep emerging. This is important as it gives breeders more choice too. A big problem is that this information doesn't get around so people may feel they have very narrow choices.

People can see a an explanation of MRIs in cavaliers and see links to a number of cavalier MRI images here.